My overall objectives are: 1) to define the mechanisms involved in the regulation of protein synthesis and degradation in the intestinal mucosa in normal conditions; 2) to define the chemical composition and function of proteins in the intestinal brush border; and 3) to study proteins involved in intestinal ransport systems. Studies will be extended to human tissue as well as animal mucosa and, where appicable, to specific disease states. Presently projected specific studies include: 1. Detailed description of intestinal turnover, both carbohydrate and protein moieties, including turnover as a function of cellular position on the villus. 2. Delineation of specific enzyme systems responsible for protein turnover. 3. Biosynthesis and turnover of secretin in intestinal mucosa. 4. Mechanism of disaccharidase "induction." 5. Carbohydrate content of disaccharidases and its relationship to enzymatic ffnction. 6. Studies of lactase during different stages of embryonic development. 7. Characterization of intrinsic factor binding site in ileum.